This invention relates to gun ammunition, and specifically to gun ammunition in which a round of the ammunition includes a casing which houses gunpowder and a projectile. More specifically, the present invention relates to multi-component gun ammunition projectiles having one or more powder-based cores disposed within a cup-shaped jacket having an open end and a seal (cap) for the open end of the jacket.
Of relatively recent vintage is a gun ammunition projectile which is fabricated from two or more metal powders. Commonly, the metal powders are die-pressed into a cylindrical geometry. Such pressed compacts are at times referred to as xe2x80x9ccoresxe2x80x9d. To form a projectile, at least one core is placed in a hollow cup-shaped metal jacket having one end thereof closed and its opposite end open for the receipt of the core. After the core has been placed in the jacket, a disc is introduced into the jacket. Employing axially directed pressure applied to the disc, the core(s) is seated against the closed end of jacket and the disc is deformed to form a seal diameterally of the jacket sufficient to prevent the escape of powder particles from the core during subsequent manufacturing operations. The open end of the jacket, that end of the core adjacent the open end of the jacket, and the disc are thereafter die-formed to define an ogive on the leading end of the jacket. The formation of the ogive tends to partially crush that portion of the core which is involved in the formation of the ogive, generating unbonded metal powder particulates adjacent the leading end of the projectile. In those projectiles where the ogive end of the projectile is not fully closed, this unbonded powder is free to escape from the projectile during handling of a round of ammunition which includes the projectile, while the round is in a gun, or after the round has been fired. Also loose powder particulates within the jacket of the projectile also may be spun to one side of the jacket, causing nutation of the spinning projectile as the projectile is traveling to a target.
In U.S. Pat. No. 5,789,698, the present inventor disclosed the use of a solid metal disc, initially formed externally of the jacket of the projectile as a disc of uniform thickness and density, to be placed within the jacket adjacent the exposed end of the core prior to formation of the ogive. As the ogive is formed, this disc is also deformed and urged toward the open end of the jacket where it remains to seal the open end of the deformed jacket and prevent the escape of metal powder from the ogive end of the projectile.
Whereas these solid metal discs are effective for their intended purpose, their cost of manufacture and/or other factors have raised the need for a different type disc. One such disc conceived by the present inventor is disclosed in copending U.S. patent application Ser. No. 09/491,257, filed Jan. 26, 2000, entitled: Powder-based Disc for Gun Ammunition Having a Projectile Which Includes a Frangible Powder-based Core Disposed Within a Metallic Jacket. The disc of this copending application comprises a metal powder, particularly a tin metal powder, which is die formed into a disc of a preselected diameter, and which is of uniform cross-sectional thickness, is uniform in density throughout the disc, and which is deformable when deployed in a projectile jacket with a core, and the open (leading) end of the combination is die-formed to define an ogive on the leading end of the multi-component projectile.
A further powder-based disc is disclosed by the present inventor in a U.S. Provisional patent application filed Apr. 30, 2001, entitled: Method of Manufacture of a Powder-based Cap for a Gun Ammunition Projectile. In this latter cap, a powdered metal is die-formed into a disc, heat treated to about its liquification temperature, and quenched to provide at least a disc having a central core of metal powder particulates encased in a skin formed by the melding of adjacent metal powder particles as the headed disc is quenched.
The present invention provides a method of manufacture of a multi-component projectile for gun ammunition, particularly ammunition for guns of 50 caliber or smaller caliber""s, such as the military 5.56 mm round, among others. The method includes the steps of providing a uniformly spherical ball of a ductile metal, either solid metal or a self-supporting pressed compact of metal powder particles, inserting the metal ball into the open end of a cup-shaped jacket which houses at least one core. The ball is disposed between that end of the core adjacent the open end of the jacket and the open end of the jacket. Thereafter, through the application of axially directed pressure against the ball, the ball is deformed into a generally flat disc. Simultaneously, the core may be seated within the closed end of the jacket. Thereafter, the jacket/core/disc combination is placed in a die suitable for the formation of an ogive on the open end of the jacket and axially directed pressure applied to the closed end of the jacket is employed to force the open end of the jacket (with the disc and a portion of the core) into the ogive-defining die cavity. This action deforms that end of the core adjacent the ogive, the disc and the open end of the jacket into the desired ogive geometry, the disc being deformed into a cap of generally hollow hemispherical geometry and containing powder particles from the core within the hollow of the cap.
The ball of the present invention may be formed as a solid metal ball or may be formed by compressing a quantity of metal powder particles into a spherical geometry having uniform density throughout the pressed compact. The advantages of the present invention include the ability to prepare, externally of the jacket, a member of very precise diametral dimension, uniform density throughout, and having the desired ductility property, at a low cost of manufacture, and which is readily fed into a jacket atop a core disposed within the jacket, by mechanical means. Moreover, the spherical geometry of the ball provides for accurate placement of the ball with its diameter aligned with the longitudinal centerline of the jacket, thereby enhancing the uniformity of the density distribution of ball (disc) about the longitudinal centerline of the jacket, hence along the spin axis of the resulting projectile, hence enhanced spin stability of the projectile as it travels along its trajectory to a target.